全文获取类型
收费全文 | 847篇 |
免费 | 54篇 |
出版年
2022年 | 7篇 |
2021年 | 6篇 |
2020年 | 6篇 |
2019年 | 3篇 |
2018年 | 8篇 |
2017年 | 9篇 |
2016年 | 17篇 |
2015年 | 25篇 |
2014年 | 21篇 |
2013年 | 68篇 |
2012年 | 37篇 |
2011年 | 50篇 |
2010年 | 22篇 |
2009年 | 23篇 |
2008年 | 45篇 |
2007年 | 49篇 |
2006年 | 49篇 |
2005年 | 49篇 |
2004年 | 58篇 |
2003年 | 52篇 |
2002年 | 51篇 |
2001年 | 19篇 |
2000年 | 15篇 |
1999年 | 12篇 |
1998年 | 13篇 |
1997年 | 10篇 |
1995年 | 9篇 |
1994年 | 4篇 |
1993年 | 11篇 |
1992年 | 10篇 |
1991年 | 12篇 |
1990年 | 8篇 |
1989年 | 12篇 |
1988年 | 8篇 |
1987年 | 4篇 |
1986年 | 7篇 |
1985年 | 6篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1982年 | 9篇 |
1981年 | 6篇 |
1980年 | 5篇 |
1979年 | 6篇 |
1978年 | 16篇 |
1977年 | 3篇 |
1974年 | 5篇 |
1972年 | 6篇 |
1971年 | 3篇 |
1970年 | 4篇 |
1965年 | 2篇 |
排序方式: 共有901条查询结果,搜索用时 15 毫秒
121.
122.
Y Ogawa K Nakao H Arai O Nakagawa K Hosoda S Suga S Nakanishi H Imura 《Biochemical and biophysical research communications》1991,178(1):248-255
We isolated several complementary DNA (cDNA) clones encoding a non-isopeptide-selective human endothelin receptor (ETBR) from a human placenta cDNA library. The clones, different in the length of their 3'-untranslated regions, encoded the same 442-amino acid protein with a transmembrane topology similar to that of other G protein-coupled receptors. The rank order of the binding of ET isopeptides (ET-1, ET-2 and ET-3) to the receptor expressed in COS-7 cells was ET-1 = ET-2 = ET-3. Northern blot analysis identified three mRNA species, 4.3 kb, 2.7 kb and 1.7 kb in size, probably generated by their use of alternative polyadenylation sites. These mRNAs were expressed in a wide variety of human tissues, at the highest level in the brain and at a significant level in cultured endothelial cells. 相似文献
123.
124.
Temperature-Sensitive Formation of the DNA Replication Complex in Adenovirus 31-Infected Cells 总被引:3,自引:2,他引:1
下载免费PDF全文
![点击此处可从《Journal of virology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
A temperature-sensitive mutant of adenovirus 31 was defective in formation of the DNA replication complex, suggesting the existence of a virus-coded protein necessary for the complex-formation. 相似文献
125.
Numerous radionuclides were released from the Fukushima Daiichi Nuclear Power Station (F1-NPS) in Japan following the magnitude 9.0 earthquake and tsunami on March 11, 2011. Local residents have been eager to calculate their individual radiation exposure. Thus, absorbed dose rates in the indoor and outdoor air at evacuation sites in the Fukushima Prefecture were measured using a gamma-ray measuring devices, and individual radiation exposure was calculated by assessing the radiation dose reduction efficiency (defined as the ratio of absorbed dose rate in the indoor air to the absorbed dose rate in the outdoor air) of wood, aluminum, and reinforced concrete buildings. Between March 2011 and July 2011, dose reduction efficiencies of wood, aluminum, and reinforced concrete buildings were 0.55±0.04, 0.15±0.02, and 0.19±0.04, respectively. The reduction efficiency of wood structures was 1.4 times higher than that reported by the International Atomic Energy Agency. The efficiency of reinforced concrete was similar to previously reported values, whereas that of aluminum structures has not been previously reported. Dose reduction efficiency increased in proportion to the distance from F1-NPS at 8 of the 18 evacuation sites. Time variations did not reflect dose reduction efficiencies at evacuation sites although absorbed dose rates in the outdoor air decreased. These data suggest that dose reduction efficiency depends on structure types, levels of contamination, and evacuee behaviors at evacuation sites. 相似文献
126.
Eiko Kawamura Gina B. Hamilton Ewa I. Miskiewicz Daniel J. MacPhee 《BMC developmental biology》2018,18(1):19
Background
Integrins are transmembrane receptors that mediate cell–extracellular matrix (ECM) and cell-cell adhesion and trophoblast cells undergo changes in integrin expression as they differentiate. However, the mechanism(s) of integrin activation leading to integrin-mediated signaling in trophoblast cell differentiation is unknown. The Fermitin family proteins are integrin activators that help mediate integrin-mediated signaling, but have never been studied in detail within the human placenta. Thus, we examined the spatiotemporal pattern of expression of Fermitin family homolog-2 (FERMT2) in human chorionic villi throughout gestation and its role in trophoblast-substrate adhesion and invasion.Methods
Placental villous tissue was obtained from patients undergoing elective terminations by dilatation and curettage at weeks 8–12 (n =?10), weeks 13–14 (n =?8), as well as from term deliveries at weeks 37–40 (n =?6). Tissues were fixed, processed and sections utilized for immunofluorescence analysis of FERMT2 expression during gestation. Additionally, HTR8-SVneo human trophoblast cells were transfected by electroporation with FERMT2-specific siRNAs or non-targeting siRNAs (control) and used in cell-substrate adhesion as well as invasion assays.Results
FERMT2 was more commonly expressed in the basal domain of villous cytotrophoblast cells and prominently localized around the periphery of individual extravillous trophoblast cells. siRNA-mediated knockdown of FERMT2 in HTR8-SVneo cells resulted in significantly decreased trophoblast-substrate attachment (p <?0.05) as well as significantly decreased trophoblast invasion (p?<?0.05) relative to control cells.Conclusions
The detection of FERMT2 throughout extravillous trophoblast columns and the results of invasion assays demonstrated that this protein is likely an important regulator of integrin activation in extravillous cells to modulate migration and invasion.127.
A 3-Mb Sequence-Ready Contig Map Encompassing the Multiple Disease Gene Cluster on Chromosome 11q13.1-q13.3 总被引:1,自引:0,他引:1
Kitamura Eiko; Hosoda Fumie; Fukushima Michiyo; Asakawa Shuichi; Shimizu Nobuyoshi; Imai Takashi; Soeda Eiichi; Ohki Misao 《DNA research》1997,4(4):281-289
Despite the presence of several human disease genes on chromosome11q13, few of them have been molecularly cloned. Here, we reportthe construction of a contig map encompassing 11q13.1q13.3using bacteriophage P1 (P1), bacterial artificial chromosome(BAC), and P1-derived artificial chromosome (PAC). The contigmap comprises 32 P1 clones, 27 BAC clones, 6 PAC clones, and1 YAC clone and spans a 3-Mb region from D11S480 to D11S913.The map encompasses all the candidate loci of Bardet-Biedlesyndrome type I (BBS1) and spinocerebellar ataxia type 5 (SCA5),one-third of the distal region for hereditary paraganglioma2 (PGL2), and one-third of the central region for insulin-dependentdiabetes mellitus 4 (IDDM4). In the process of map construction,61 new sequence-tagged site (STS) markers were developed fromthe Not I linking clones and the termini of clone inserts. Wehave also mapped 30 ESTs on this map. This contig map will facilitatethe isolation of polymorphic markers for a more re.ned analysisof the disease gene region and identi.cation of candidate genesby direct cDNA selection, as well as prediction of gene functionfrom sequence information of these bacterial clones. 相似文献
128.
Kentabo Tanaka Mikio Tamaki Takuzì Itoh Eiko Otaka Syozo Osawa 《Molecular & general genetics : MGG》1972,114(1):23-30
Summary Mutants from Escherichia coli Q13 were selected for resistance to leucomycin, tylosin or spiramycin. Most of the mutants so selected exhibited cross resistance to all the macrolide antibiotics tested including erythromycin. A few mutants however seem to be less resistant to erythromycin. One mutant, QSP008, was highly resistant to tylosin, leucomycin and spiramycin but relatively sensitive to erythromycin. Another mutant, QSP006, was highly resistant to spiramycin but less resistant to erythromycin, tylosin and leucomycin. This selective resistance of cells to specific antibiotics could be due to the extent of conformational alteration of their ribosomes, which may be demonstrated by the extent of 14C-erythromycin binding to these ribosomes. The ribosomes from QSP008 cells were found to contain an altered 50-8 protein of the 50s ribosomal subunit, while in the ribosomes from QSP006 no such protein change could be detected by the methods used.A preliminary data of part of this work has been published (Tanaka, Teraoka, Tamaki, Watanabe, Osawa, Otaka, and Takata, 1971). 相似文献
129.
Eiko Otaka Takuzi Itoh Syozo Osawa Kentaro Tanaka Mikio Tamaki 《Molecular & general genetics : MGG》1972,114(1):14-22
Summary Chromatographic analyses on a Dowex 50x8 column of tryptic digests of the mutationally altered 50-8 protein component from several erythromycin resistant (ery
r) mutants of Escherichia coli and Escherichia freundii have been performed. It was found that (1) the difference in the elution profile of the altered components detected with carboxymethyl cellulose column chromatography reflects the difference in their amino acid sequence, (2) the structural change(s) of the 50-8 protein from three E. coli ery
r mutants examined seems to exist only in the same single peptide fragment and (3) the primary structure of the 50-8(R) protein of E. freundii (ery
s: wild type) differs from that of E. coli Q13 (ery
s) and the structural change in 50-8(R) component of E. freundii caused by the ery
r mutation was found to take place in different peptide fragments from that in which the mutational change of the E. coli 50-8 component occurred. 相似文献
130.
Role of genes 46 and 47 in bacteriophage T4 reproduction. II. Formation of gaps on parental DNA of polynucleotide ligase defective mutants 总被引:14,自引:0,他引:14
The nature of nucleolytic activity regulated by genes 46 and 47 of bacteriophage T4 was studied by examining the metabolism of parental DNA of phages carrying a mutation in polynucleotide ligase gene (lig) and an additional mutation in one of the following D0 genes (D0 genes are necessary for T4 DNA synthesis): 32, 43 (DNA polymerase pol), 44 and 45. Polynucleotide ligase and DNA polymerase were used to distinguish nicks (phosphodiester bond interruptions on duplex DNA) from gaps (interruptions with missing nucleotides). In non-permissive hosts, parental DNA of double mutants (lig, D0) accumulated both single- and double-strand breaks. Up to 30% of this DNA eventually became acid-soluble. An additional mutation in gene 46 (or 47) did not prevent accumulation of double- and single-strand breaks but did prevent degradation to the acid-soluble state. The majority of the single-strand breaks on (lig, D0)-DNA were presumed to be gaps since, after extraction from infected host cells, they were repaired by ligase plus DNA polymerase but not by ligase alone. In contrast, the majority of the single-strand breaks on parental DNA of (lig, D0, 46) or (lig, pol, 47) were repaired by ligase alone, suggesting nicks, rather than gaps. These observations suggest that (i) genes 46 and 47 regulate, either directly or indirectly, an exonuelease activity which can attack T4 DNA at nicks to create gaps, and (ii) T4 DNA polymerase, and the products of genes 32, 44 and 45 are necessary to prevent nicks from becoming gaps in vivo. Possible roles for genes 46 and 47 in T4 DNA replication and in recombination are discussed. 相似文献